The present invention relates generally to a method and apparatus for making a core plate having a friction material facing. More specifically, the invention is directed to a method and apparatus for making a friction plate having multiple segments of friction material on a core plate.
The present invention relates to a method and apparatus for making friction materials for use with a wet-type multi-plate clutch. The multi-plate clutches generally comprise a plurality of interleaved clutch discs and clutch plates which engage to provide the transmission of energy from a drive engine to a drive wheel. Wet-type clutches also utilize a lubricant such as oil to reduce clutch wear, cool the friction facings of the clutch discs, and provide desired hydrostatic forces between the clutch plates and clutch discs.
The friction material is usually composed of sintered metal or paper which normally is impregnated with a phenolic based resin. The friction material is commonly cut from sheets of the friction material. The sheet of material is fed through a die cutting apparatus which punches out the desired shape of the friction material from the sheet. The desired shaped friction material is then separated from the remaining, or scrap, material.
The friction material is relatively expensive and, therefore, it is desirable to optimize amount of friction material used and to eliminate waste from the manufacturing process.
Further, the elimination of any scrap or waste product from the manufacturing process assists in meeting various industry compliance standards. Also, the proper disposal of any scrap is the focus of increasing environmental regulation. Any scrap resulting from the manufacturing process must be disposed of in an appropriate manner. This is a concern since the manufacturing of friction materials generally uses expensive materials. Thus, the disposal of scrap friction material is becoming increasingly costly.
Another, and sometimes competing, concern is that the friction material must continue to meet the increasing demands required by the newly developing engines, clutches, transmissions, and the like. It is therefore important that sufficient cooling and lubrication of the friction material and clutch plates occurs such that smooth engagement and disengagement of the clutch is maintained, without creating excessive wear on the members of the clutch and friction facing material. The designs of many prior art friction material incorporate the use of grooves or slot patterns within the facing material to achieve the desired cooling and lubrication by allowing the passage of a fluid such as oil through the friction facings. Such cooling grooves are generally produced from one of three labor intensive methods.
One method provides that the friction material is pre-grooved prior to being cut and applied to the clutch plate is shown by Nels U.S. Pat. No. 4,260,047. Another method of producing grooves uses a configured tooling to compress portions of the friction material during the hot pressure bonding process. Yet another method involves producing cut grooves in a finished friction plate by mounting the friction plate onto a fixture and passing multiple milling and grinding wheels through the friction material to cut distinct grooves of desired depth and definition.
In addition, numerous clutch designs for producing a large variety of friction facing materials and designs of friction facing materials are known. Several common friction facings, currently available, are shown by the disclosures of Nels U.S. Pat. No. 4,260,047 and Mannino, Jr. U.S. Pat. No. 4,674,616. These friction discs, which are for use with clutches, are formed from friction material and produced from the joining of a plurality of separate arcuate segments. The arcuate segments are pre-grooved to allow cooling oil to flow over the friction facing during clutch operation.
The Fujimoto et al. U.S. Pat. No. 5,094,331, Quigley U.S. Pat. No. 5,460,255, Stefanutti et al. U.S. Pat. No. 5,776,288, Quigley U.S. Pat. No. 5,897,737 and Willworth et al. U.S. Pat. No. 6,019,205 disclose clutch friction plates having a large number of friction material segments on the plate. The segments are in a spaced apart relationship such that an oil groove is provided between every adjacent segment.
The Marin U.S. Pat. Nos. 3,871,934 and 4,002,225 show a friction material wound around the outer periphery disc, such that the friction material overlaps the disc on both sides. The overlap is then cut at intervals around the periphery and folded onto the surface of the disc.
The Takakura et al. U.S. Pat. No. 5,335,765, discloses a friction member having sets of first grooves and second grooves disposed in a radial plane and inclined obliquely backwardly in relation to the direction of rotation.
The Nels U.S. Pat. Nos. 5,615,758 and 5,998,311 show friction yarn facing materials with no grooves, but rather, the warp and fill yarns form channels to allow for the flow of fluid therethrough.
The common failing of the previous designs of the apparatuses for making segmented friction materials lies in the formation of the intricate shapes and designs of the segments of friction material themselves, which, consequently, leads to manufacturing complexities, increased scrap production, and the resultant concerns regarding proper disposal of the scrap. Further, these intricately shaped friction materials are all individually manufactured to meet specific requirements for specific types of friction clutches and, generally speaking, cannot be used in a wide variety of applications.
For example, the Miyaishi et al. U.S. Pat. No. 5,571,372 shows one manufacturing method which produces about 20% scrap and describes a device which cuts and holds individual sections of friction material until a spring-like mechanism is engaged to dispense the individual portions on the core plate.
Therefore, there is a need for an apparatus to manufacture a friction clutch plate having distinct cooling groove patterns of desired depth and definition without the need for secondary operations and attendant machinery.
There is a further need for an apparatus for making a multiple segment friction material which is essentially scrapless in its manufacture.
There is still another need to provide a method and apparatus for making a friction material which apparatus has structural advantages designed to enhance production performance of the core plate with the friction material, and specifically increased durability, reduced drag and reduced hot spotting.
There is a still further need for a friction material which is universally applicable to differing types of clutches and friction plates.